1. Field of the Invention
The present invention relates to power supplies and is particularly concerned with redundant power supplies which are provided with connectors for the input and output voltages.
2. Description of the Prior Art
Unless special measures are taken, a collapse of the output voltage of a power supply and, therefore, a temporary or permanent disruption of the system operation occurs in electronic systems supplied by redundantly-operated power supplies when the second power supply is plugged in, for example after a repair. This disruption is caused in that the output capacitor, already charged to the operating voltage, of the power supply already in operation has the uncharged output capacitor of the power supply being plugged in connected in parallel thereto when the second power supply is plugged in and this leads to a collapse of the operating voltages.
The invention relates to an apparatus for a redundant power supply comprising a receptacle apparatus and at least two power supply inserts which are insertable into the receptacle apparatus and which are mechanically supported in the receptacle apparatus in their inserted condition, whereby the receptacle apparatus and the power supply inserts are provided with plug connectors which comprise contact members for the input voltage and contact members for the output voltage of the respective power supply insert, whereby the power supply insert contains an output capacitor which is respectively, directly connected to the plug connector of the power supply insert.
U.S. Pat. No. 4,177,389, fully incorporated herein by this reference, discloses such an apparatus. In this known apparatus for a redundant power supply, two regulated power supply devices which are electrically connected in parallel at the output side are provided. Both devices are constructed in identical fashion. The power elements of the power supply inserts are connected directly parallel only with their grounded negative poles. The positive poles are interconnected via two strapping plugs. The power element and the appertaining strapping plug are structurally designed such that a removal and insertion of the power element is not possible until after the appertaining strapping plug has been removed. It is assured by these measures that, when the power element is plugged in, an output capacitor is first charged via two resistors without influencing the load feed. The strapping plug can then be inserted and the power element can be subsequently placed in operation.
Another solution of the problem initially mentioned consists of incorporating a respective diode in the line between the output capacitor of each power supply and the parallel circuit point, these diodes only permitting an energy flow in the direction from the power supply device toward the load. The initially-described voltage collapse is thereby avoided without special structural measures being required therefor.
The voltage drop arising at these diodes, however, reduces the efficiency of the devices and increases the load-dependent output voltage fluctuations. The use of such decoupling diodes can therefore prove not permissible, particularly given low operating voltages and given a requirement of narrow tolerances.
U.S. Pat. No. 3,993,935, fully incorporated herein by this reference, discloses an assembly of data technology which has a plug connector with leading contacts. Achieved with the assistance of this plug connector is that, when the assembly is placed in operation, i.e. when the pin strip is plugged into an appertaining spring clip of a receptacle, the operation of the data processing device is not disrupted in that undefined operational conditions prevail at first and faulty signals are output onto a bus system. It is thereby specifically seen to that, when the plug connection is produced, the transmitter and the receiver are first supplied with operating voltage and control logic and a buffer memory are supplied with operating voltage and a reset potential. Further achieved with the assistance of current wipers that are respectively extended across a plurality of contact pairs is that certain connections are only produced after a completely inserted pin strip has been inserted free of cants. This applies, for example, to the connection of a reset input to a reset signal bus and to the supply of the operating voltage to circuits given an open collector output.
In the circuits having an open collector output, a finite capacitance is effective at the output, so that a load current flows from the bus line into these capacitances immediately after the plug connection has been produced. In order to thereby avoid voltage collapses on the bus line, an additional capacitor is disposed on the side of the bus line. An apparatus for limiting the plugging speed is not provided.